The present invention generally relates to the field of workstations, and more particularly to heavy duty workstations for modular assembly cells having work surfaces of which the height above a supporting floor is adjustable.
Workstations, also known as manufacturing cells, are often used in manufacturing facilities for operations on workpieces and for assembling parts to form assemblies or subassemblies. Workstations may be configured in a manner similar to that of conventional workbenches, typically having a generally flat work surface or platform for holding a workpiece while performing manufacturing operations such as fabricating, drilling, assembling, etc. Workstations may also be configured to include manufacturing tooling (e.g., an air cylinder, a power drill, screwdriver, or nut runner, riveting or spot-welding apparatus, etc.), instrumentation and/or control apparatus (e.g., for monitoring and controlling a manufacturing process or characteristic of the workpiece), parts and product bins, trays, conveyors, etc.
In the past, workstations were typically designed and built for a particular manufacturing application or procedure. In most cases, the height of the work platform is fixed. The workstation or cell is normally constructed by mounting a support structure to a table. The table may be constructed from welded steel, or assembled from aluminum extrusion or steel tubing. The workstation tooling is typically mounted to the support structure in a fixed location above the work platform at an average height normally required for the assembly operation. Since each workstation is normally associated with a particular manufacturing function and a unique workpiece, the height of the support structure necessarily varies for nearly every workstation. The type of the tooling also varies from workstation to workstation. Hence, numerous different designs for the workstation support structure are often required to accommodate a single manufacturing line.
Furthermore, different workstation operators may be assigned at different times to work at a particular workstation, and all operators are obviously not the same height. Since a particular workstation may be used for assembling different products having different heights at different times, it is therefore desirable for the height of the working surface to be adjustable above the floor. Preferably, the height would be infinitesimally adjustable, or at least adjustable in small increments to accommodate all operators. Most fixed-height workstation constructions are not easily re-configurable to make them adjustable in height. The fixed working height of most known workstations creates a less than ideal ergonomic situation for the operators.
Some commercially available workstations are designed to have work surfaces adjustable in height. However, such workstations have numerous disadvantages. First, adjustable-height workstations have generally been of relatively small capacities in terms of weight and force that the adjustable work surface can support, e.g., often having a support capacity of less than 1000 pounds. Second, those few heavy-duty workstations that are height-adjustable are usually only adjustable in large increments. Third, such heavy-duty workstations have been relatively expensive. Fourth, those workstations that are infinitesimally adjustable in height are usually not heavy duty, and therefore tend to slip under increased loads. Fifth, known workstations often require a difficult or involved procedure to adjust the height to a different operator or workpiece. Sixth, workstations that are provided with tooling for manufacturing a particular product generally had the tooling affixed in a manner that makes it difficult to remove and replace with different tooling for another product. These disadvantages present significant difficulties in implementation of flexible manufacturing cell concepts and practices.
A need, therefore, exists for an infinitesimally adjustable-height work surface for a workstation that is very rugged in construction to accommodate relatively heavy workpieces and large forces, that can be adjusted quickly and easily to accommodate flexible manufacturing cell environments, and that is relatively inexpensive and easy to manufacture.
It is an object of the present invention to provide a workstation having a work surface that is infinitesimally adjustable in height with respect to a supporting floor.
It is another object of the present invention to provide an adjustable-height workstation that is ruggedly constructed and has a workpiece weight capacity and manufacturing force capacity exceeding 1000 pounds.
It is a further object of the present invention to provide a workstation in which an increase in a load force causes a corresponding increase in a work surface securing force to prevent slippage.
It is still another object of the present invention to provide a rugged, adjustable-height workstation that is relatively inexpensive to manufacture.
It is yet another object of the present invention to provide a workstation that facilitates the use of manufacturing tooling that can be easily removed and replaced to enable manufacturing of different products at the same workstation.
Accordingly, the present invention provides a workstation that is designed to be both height-adjustable for different operators and re-configurable for different products. In the preferred embodiment, the base structure of the workstation is constructed from a relatively inexpensive weldment and a vertical column composed of a standard structural steel I-beam. Only minimal machining of this I-beam is required to manufacture the workstation. A steel tooling plate is vertically disposed and mounted to the vertical column using channels such that it is able to slide vertically. A horizontal platform, along with the necessary support structure, is mounted to the vertical tooling plate to provide the work surface for the workpiece. Alternatively, a horizontal platform can be used that supports a conveyor when a part transport system is required. A locking wedge mechanism is located between the vertical column and the vertically disposed tooling plate to frictionally engage the surface of the column. This locking wedge allows the tooling plate to be positioned anywhere within a range along the vertical column and then locked. The vertical adjustment can be made using a hydraulic jack permanently attached to the workstation, or using a crane or forklift. The locking wedge mechanism allows for extremely heavy tooling or workpieces to be securely affixed to the vertical tooling plate, while maintaining its ability to be readily adjusted along the vertical column.
Another embodiment of the present invention provides a support structure for a work surface, the support structure including a beam having a length and a surface, a position securing apparatus, and a workpiece-supporting device. The workpiece-supporting device is configured to be slidably restrained to the beam and to be secured to the beam in selected positions along the length of the beam by the position securing apparatus. The position securing apparatus is configured to constrain the workpiece-supporting device in the selected position notwithstanding the presence of a load force having a line of action parallel to the longitudinal axis of the beam. The position securing apparatus is further configured to exert a constraining force that is proportional to the load force.
Still another embodiment of the present invention relates to a workstation including a means for supporting a workpiece, and a means for supporting the means for supporting the workpiece at a selected distance above a floor. The workstation also includes a means for frictionally securing the means for supporting the workpiece to the means for supporting the means for supporting the workpiece at the selected distance. The means for frictionally securing includes a first surface frictionally bearing upon a second surface.
Yet another embodiment of the present invention relates to a workstation including a vertically disposed support member and at least one generally vertically disposed tooling plate assembly. The tooling plate assembly includes a tooling plate and a position securing apparatus for securing the tooling plate in a selected vertical position with respect to and upon the support member. The position securing apparatus includes first and second wedging surfaces configured to cooperate in frictionally securing the tooling plate to the support member. The first and second wedging surfaces are disposed to be engaged in a downward direction of movement of one of the first and second wedging surfaces. An increase in downward force upon the tooling plate increases engagement of the first wedging surface with the second wedging surface and increases frictional securing force, the securing force thereby corresponding to the loading force.